Barium Metaborates

The inhibitive properties of molybdate-based anticorrosive pigments are attributed to the ability of molybdate ions to pass into solution, and to migrate to the metal surface resulting in the formation of a protective layer on the substrate, which insulates (passivates) the metal from attack and prevents corrosion [5.91]. 

The use of the pure molybdate-based pigments available on the market is limited due to their cost [5.53, 5.56]. To overcome this disadvantage, molybdate, and phosphate pigments are combined (see Section 5.2.5.2.) or molybdate compounds are apphed to inorganic fillers like calcium carbonate and/or zinc oxide [5.56, 5.91]. 

Compared to the pure modified molybdates, those combinations are difficult to disperse [5.53]. Micronized versions of combined molybdate based pigments that are available today as easily dispersible grades are summarized in Table 5.10 [5.91]. 

Characteristic Unit Caicium zinc moiybdate Caicium zinc phosphate moiybdate Zinc molybdate Zinc phosphate molybdate 

Core material Calcium carbonate Calcium carbonate Zinc oxide Zinc oxide 

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Barium Metaborate. Barium metaborate is used both as a flame retarder and as an antihmgicide for many flexible poly(vinyl chloride) apphcations (19). 

Barium Metaborate. Three hydrates of barium metaborate, BaO 20 ate known. The tetrahydrate (147) and pentahydrate (148)... 

Barium metaborate is used as an additive to impart fire-retardant and mil dew-resistant properties to latex paints, plastics, textiles, and paper products (6). Barium metaborate is marketed by Buckman Labs, Inc., Memphis, Tennessee (12). 

Boron, as barium metaborate, is marketed as a mildew preventative for paints (273). Borax is used as a wood preservative, and an organic boron, 2,2 -(l-methyltrimethylenedioxy)-bis(4,4,6-trimethyl)-l,3,2-dioxaborinane (Biobor JF) [14697-50-80] is a biocide for jet fuel (274). Whereas tin metal is used to coat steel cans used as food containers, organic tin in the form of tributyl tin compounds have proven to be powerfiil antimicrobials, and have found use in antifouHng coatings for ship bottoms, paints, and wood preservatives (275). 

The search for new, effective anticorrosive pigments with low toxicity to replace red lead and chromates in paints has occupied the attention of many paint-making companies recently. Barium metaborate, calcium molybdate and zinc molybdate have been identified as possible compounds but they have not found general acceptance in the United Kingdom and western Europe, most probably because of their lower cost effectiveness. 

Barium metaborate [13701-59-2], BaO B203 H20, [5.78] and zinc borophos-phate [84012-98-6], ZnO x B2Oa-y P205-2H20, are colorless pigments. Their properties are listed in Table 44 their uses in various binders are listed in Table 39. They both have a relatively high water solubility. Barium metaborate is coated with silica to reduce this. 

Examples of trade names are Butrol (Buckmann Laboratories, USA) for barium metaborate, and Sicor BZN (BASF, Germany) for zinc borophosphate. 

Buckman Laboratories Inc. Barium metaborate, company information, Memphis, Tennessee, 1989. 

Barium metaborate exists in both a and J3 phases with the transition temperature at 925 5°C The a phase is centrosymmetrical and therefore exhibits no NLO response at all. The ft phase belongs to a... 

Barium chloride White precipitate of barium metaborate that is soluble in excess reagent dilutes acids as well as ammonium salt solutions... 

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